Electrical Performance of Polymer Housed Zinc Oxide Arresters Under Contaminated Conditions

The electrical performance of polymer housed zinc oxide distribution arresters has been investigated in a fog chamber. Two types of housing materials, namely, copolymers of ethylene and propylene (commonly known as EPM rubber) and terpolymers of ethylene propylene and diene (commonly known as EPDM rubber), both containing alumina trihydrate (ATH) filler, have been examined. It has been demonstrated that under relatively low (250 µS/cm) and moderate (1000 to 2000 µS/cm) fog conductivity, degradation in the form of tracking and erosion of the housing occurs. on some housings, degradation is dominant in the region of the mold line and is due to nonuniformity in filler dispersion. The electric field has been computed and a few electrode modifications to improve the surface electric field distribution are suggested.